diff --git a/src/view/widget/AphrontStackTraceView.php b/src/view/widget/AphrontStackTraceView.php
--- a/src/view/widget/AphrontStackTraceView.php
+++ b/src/view/widget/AphrontStackTraceView.php
@@ -27,13 +27,15 @@
     foreach ($trace as $part) {
       $lib = null;
       $file = idx($part, 'file');
-      $relative = $file;
-      foreach ($libraries as $library) {
-        $root = phutil_get_library_root($library);
-        if (Filesystem::isDescendant($file, $root)) {
-          $lib = $library;
-          $relative = Filesystem::readablePath($file, $root);
-          break;
+      if ($file) {
+        $relative = $file;
+        foreach ($libraries as $library) {
+          $root = phutil_get_library_root($library);
+          if (Filesystem::isDescendant($file, $root)) {
+            $lib = $library;
+            $relative = Filesystem::readablePath($file, $root);
+            break;
+          }
         }
       }